Estimating Bike Split for Ironman

zico10

How should I estimate my time for bike leg of ironman race. Obviously it's not as simple as just multiplying a 40km split in an Olympic distance by 4.5. How can I use these though as a reliable guide to what sort of time I should be doing?
As regards half distance I've done Kenmare twice and the Sperrin half-ironman back in May. It's Challenge Copenhagen which I am doing, so with Kenmare being a good bit short of 90km and being so hilly, should I be using this to make a reliable estimate of time? The Sperrin race was a couple of k short as well.
Thanks

911sc

zico10 wrote: »

How should I estimate my time for bike leg of ironman race.

What your average practice time for 180kms?

interested

zico10 wrote: »

How should I estimate my time for bike leg of ironman race. Obviously it's not as simple as just multiplying a 40km split in an Olympic distance by 4.5. How can I use these though as a reliable guide to what sort of time I should be doing?
As regards half distance I've done Kenmare twice and the Sperrin half-ironman back in May. It's Challenge Copenhagen which I am doing, so with Kenmare being a good bit short of 90km and being so hilly, should I be using this to make a reliable estimate of time? The Sperrin race was a couple of k short as well.
Thanks

IMHO
You'll obviously have done a fair few training rides on the TT bike at this stage - over varying distances. Some as part of bric sessions and some as just straight bike sessions. You'll know yourself by feel/HR etc whether you can sustain a particular pace on the day with the bit of a run to get done.

There'll be platinum,gold,silver,bronze,copper and steel bike split times that you might have in your own mind before the day that can be greatly effected positively and negatively by things you cant control. Like super slick european road surfaces, nice warm weather, wind on the course, some sort of mechanical, GI problems.

If you've trained hard enough and are fit enough to sustain your previously best 40km/tt time + x% over a long distance bike course then you'll have a ball park idea of the time it'll take you on the day.

Have confidence in the work you've done and just make sure you dont go doing anything over the final weeks that will negatively effect your race day. That one more super long bric session may not be worth it - but inevitably only you'll know.

Very best of luck

tunney

Using the chung-on-a-stick method you can calculate your Crr and Cda.
Using gas analysis in a lab you can determine the point you cross the fat:cho threshold.

Now using the cda, the crr and your wattage you can factor in the terrain of the course and come up a number.

This should be close.

Previous non IM race times and practice 180km times are completely useless.

Best bet IMHO is to forget time goals and race by pe,hr and/or wattage. Chasing a bike time will leave you walk the run.

zico10

911sc wrote: »

What your average practice time for 180kms?

Haven't actually done 180km in training yet, up to 145km in my long rides. It's just time on bike that I aim for in these rides, not looking to cover any set distance in a particular time. I will get up to this distance but from talking to people, practice rides of this nature were not a regular part of my training plan.

zico10

tunney wrote: »

Using the chung-on-a-stick method you can calculate your Crr and Cda.
Using gas analysis in a lab you can determine the point you cross the fat:cho threshold.

Now using the cda, the crr and your wattage you can factor in the terrain of the course and come up a number.

This should be close.

Previous non IM race times and practice 180km times are completely useless.

Best bet IMHO is to forget time goals and race by pe,hr and/or wattage. Chasing a bike time will leave you walk the run.

To be honest my training or indeed race strategies aren't all that scientific and it's mainly perceived effort I go on. Like most triathletes I have a HRM, but don't know enough about using it as a training tool, so decided not to get get bogged down in it for my ironman training, think in my ignorance it would just be a distraction. I look to hit a certain pace when I run and obviously there will be factors that can make this difficult, but I find it is successful for me anyway. With a much greater difference between top speed and slowest speed on a bike, it's not a strategy I can rely on on the bike.

Appreciate what you say about forgetting time goals and have heard it from other people as well. Maybe it's a bit foolhardy of me to be looking for a time in my first ironman race, but I don't want to just "get round". If I were to cross the line a good bit outside the time I have in mind, then I wouldn't feel like I'd acheived anything.